1. Field of the Invention
The present invention relates to prostheses including a silicone liner with a coupling pin, a prosthesis shaft adapted to a limb stump, provided with longitudinal slits in portions thereof, the diameter being adjustable by tightening elements, and a holding device to connect artificial limbs with the shaft of the prosthesis.
2. Description of the Background Art
The purpose of prostheses is to replace, as best as possible, limbs that were lost through an accident or illness. To temporarily attach prostheses, for example artificial hands or feet, to a limb stump, special prosthesis shafts are used, which must be anatomically fitted to the limb stump. The attachment is commonly achieved by a vacuum between the prosthesis shaft and the limb stump or between the limb stump and a silicone liner.
Prosthesis shafts are made of metal, wood or cast resin. There are shafts of longitudinal or cross-oval shape, full-contact shafts, with a valve, or a silicone liner. With amputations below the knee joint, the prosthesis shafts are somewhat triangle-shaped, with support devices on the bone structure.
Since the prosthesis shafts must be fitted to the limb stump as exactly as possible, in order to generate and maintain the vacuum providing the firm attachment, the shafts are always custom-made products, which also must provide perfect pressure distribution of the load onto the entire stump area so that the stump can optimally transfer the body weight and other forces. Since initially after an accident or amputation, there is swelling of the limb stump within a few days or weeks, which then goes down again, but from a medical and orthopedic view, the patient should be fitted with a prosthesis as quickly as possible, at times several prosthesis shafts must be fabricated individually during the rehabilitation and adjustment period alone. This is unsatisfactory because of the expenditure of time and particularly money connected therewith.
It goes without saying that there has been no lack in attempts to rectify this situation. For example, inflatable air chambers have been arranged between the prosthesis shaft and the limb stump, see WO 00/23016. However, it was determined very quickly, that the grip attachment of the prosthesis to the limb stump was clearly reduced. In particular, the utilization value of the prosthesis was greatly reduced, since it is not solidly connected to the limb stump anymore.
To circumvent this problem, DE 27 18 395 C suggests filling air chambers with little balls. The ball-filled air chambers are supposed to adapt to the contours of the limb stump. By evacuating the air chambers, the balls are supposed to be molded into their actual, more or less well-adapted, position on the limb stump. Although it was good thinking, this construction did not prove itself and was not successful in practice.
From DE Patent 314 985, which was published in 1919, a prosthesis shaft is known, which is made of an inner and an outer shell. The inner and outer shell consists of individual lamellae, which are connected to each other by a rivet, in such a way that the diameter of the inner and out shell can be modified. To alter the diameter of the inner and outer shell, several tightening strings are provided. However, after closing the tightening strings for the outer shell, the tightening strings for the inner shell are no longer accessible, that is, their fasteners are not accessible anymore. Attaching and detaching of such a prosthesis shaft is, therefore, extremely cumbersome and time-consuming. In addition, prosthesis shafts made of lamellae cannot develop a vacuum for firm attachment to the limp stump.
A further, dual-shell prosthesis shaft is known from DE Patent 323 671, which was published in 1920. Here, too, an inner and outer shell consist of lamellae, whereby the lamellae of each shell are mutually connected by a rivet in such a way that it allows modification of the diameter with the help of tightening strips. Furthermore, an upper part of the lamellae of the inner shell are movably connected with the lamellae of the outer shell. The object of this construction is to avoid gaps between the individual lamellae. This construction also did not succeed in practice.
From the orthopedic practice it is known that limb stumps not only change in width but also in length. This is, for example, the case when the end of the limb stump, which is in direct contact with the prosthesis and, for example, in the case of an upper thigh prosthesis, must bear the entire body weight of the patient, gets infected and swelling occurs. A change in length can also occur when the swollen tissue is healing after an amputation or operation, and the swelling goes down. The limb stump then no longer sits correctly with a conical bearing surface that is provided in each prosthesis shaft and can, for example, no longer optimally transfer the body weight to the prosthesis. Also, in this case, new prosthesis shafts must be fabricated or the old prosthesis shafts must be modified. This is unsatisfactory.
From DE 82 16 840 U a prosthesis shaft is known, whereby a height of the conical bearing surface for the limb stump is adjustable. The height adjustment is done using level or wedge mechanics, which can be manipulated from the outside by the patient using a crank or something similar. Height adjustment with a built-in electric motor, possibly battery-operated, is also suggested. Since the height adjustment must be installed in the custom-made prosthesis shaft, it must be enlarged and modified accordingly. This increases the expenditure of time and money.
As previously mentioned, each prosthesis shaft must be fabricated in such a way that it transfers the forces optimal to the limb stump. To accomplish this, the prosthesis shaft must be suitably inflexible. In order to be able to adjust the diameter, the prosthesis shaft must be flexible. Flexibility directed towards the diameter can be achieved by construction with lamellae, as described in the German patents listed above. The connection between the lamellae with only one rivet, however, has the disadvantage that it weakens the stability of the prosthesis shaft.